Supporting structure for floating tank roofs



Sept. 21, 1943. J. H. WlGGlNS SUPPORTING STRUCTURE FOR FLOATING TANKROOFS Filed Feb. 12, 1942 Patented Sept. 21, 1943 SUPPORTINGsTRUoTUnEjFoR FLQATING f A KROQFS 3 John H. Wiggins, Chicago, in;Application February 12,1942, Serial red-430,532;

2 Claims. ((1220-26) This invention relates to liquid containers of the.type that are equipped with a floating roof, and particularly, to themeans used in such structures for supporting or sustaining the weight ofthe roof when the roof is not floating on liquid in the container. I

One object of my invention is to provide an improved auxiliarysupporting structure for a float ing roof, which is of such design thatwhen cleaning of the container becomes necessary,said auxiliary'supporting structure can be adjusted or manipulated so as to cause theroof to be. sustained at a level high enough above the bottom of thecontainer to provide ample clearance .for workmenengaged in theoperation of removing sediment that has collected on the bottom of thecontainer.

Another object is to provide a supporting means fora floating tank roof,that has provision for sustaining the roof in either one of twodifferent levels when the tank is empty, or substantially empty, andwhich can beproperly adjusted or manipulated while the roof is floatingon liquid in the tank, so as to select the particular level at which itis desired to support the roof, when. the liquid is discharged from thetank.

Andstill another object of my invention is to provide a floatingtank'roof that is equipped with a plurality of horizontally-slidable,auxiliary supports-that are mounted on theroof in such away that theyare'operable from the top side of the roof, but nevertheless, are hiddenfrom view and protected from the weather. Other objects and desirablefeatures of my invention will be here: inafter pointed out.

Figure 1 of the drawing is a vertical transverse sectional view of apontoon type floating roof constructed in accordance with my presentinvention, showing the roof floating on liquid in the container, andillustrating the horizontallyslidable, auxiliary supports arranged intheir in-' active position.

Figure 2 is a similar view, showing the roo floating on the liquid, andillustrating the auxiliary supports in their active position.

Figure 3 is a vertical, transverse sectional view, illustrating how saidhoriZontally-slid'able, auniliary upports co-act with thefixed orstationary supporting structure insideof the container to maintain theroot high enough above the bottom of the container to provide ample headroom or clearance for workmen engaged in the operation of cleaning thecontainer; and 1 Figure' i is an emarged'sectional v 'w, taken on theline 45-4 ofFigureZ, looking in the direction indicated by the arrows. uI l Inthe accompanying drawing which illustrates the preferred formbf myinvention, A designatesa liquid container, such as an oil storage tank,and Bdesignates .asanentirety a floating roof which normallyv 'floatsupon liquid :1: in the tank, said roof comprising; a limber metal deck[that is attached to the upper end of, an annular pontoon c locatedatthe periphery of the roof.

My invention consists of a supporting means.

. for the roof B, which isof such construction that it will sustaintheroof at either one of two difierent levels when the tank is empty orinotfilled with sufiicient-liquidlto float the roof. I One of said levelsconstitutes the lowermost position of the roof, and the. other levelconstitutes the position of the roof when the bottom of the tank isbeing cleanedto remove sediment that has collected'thereom Preferably,the roof is sustained inits lowermost pjosition,or atlthe low level, bya fixed or stationary supporting structure D in the lower portion of.the tank A, disposed so thatthe pontoon C of the roof willcometo restthereon when the level of the liquid in the tank drops to a point belowthe top surfaceof said support-' ing structure ll-lilhe particularconstruction of the supporting structure D is immaterial. It'mayconsistof short standards oruprights that project upwardly from thebottom ofthe tank A in proximity to the side wall of the ;tank,or' it may,

consist of a framework on the bottom ofthe tank that extendscircumferentially around the tank adjacent the tank side wall. The roofis sustained at the high level or in tank cleaning position, by

aplurality of horizontally-slidable, auxiliary supports E on the, roof,that areadaptedto beshifted into a .positionwherein they co -act withthe fixed. or stationary supporting structure D, to in effectincreasethe height of same, or in other words,

form upwardly-projecting extensions on the stationary supportingstructure D,'on which the pontoon of the roof comes to'rest, during theoperation of emptying the tank, thereby causing the roof tobe supportedhighenough above the bottomof the tank to proyide ample head room forworkmen engaged in cleaning the tank.

The horizonta1lys1idable,- auxiliary supports E .canbe mounted on theroof B' invarious ways without departing from thesp-irit of myinvention, but I prefer to suspendthem from theunderside of the roof insuch'amannerthat-they are operable from the top side of the-rooi when rthe roof is floating, and can be easily shifted from a normally inactiveposition into an active position, wherein they are disposed underneaththe pontoon C of the roof. When the auxiliary supports E are in theirinactive position, shown in Figure 1, they are disposed out of verticalalignment with the pontoon C of the roof and the fixed or stationarysupporting structure D inside of the tank, and accordingly, do notinterfere with the rise and fall of the roof, in response to variationsin the level of the liquid :0 on which the rooffloats. 'Also,'-wh'en thelevel of theliquid drops to such -'a point that the pontoon of the roofmoves downwardly onto the fixed or stationary supporting structure D,the auxiliary supports E do not interfere with the downward movement ofthe roof, due, of corirsetb'thefact that said auxiliary supports E liein a different vertical plane than the plane in which the po'ntoon C andstationary supporting struoture D are disposed. When it becomesnecessary to remove sediment that has collected on'tlie-iiottom of thetank A, the auxiliary supports E are shifted "horizontally intoth'eiractive' position. L as shown in Figure 2. Subsequently, when "the liquid"as is discharged from the tank "to; empty the tank, the "roof jjmoves"downwardly until the auxiliary supports E come in contact with thestationary supponting'structure D, thereby eansing'the root to besuppofted' or sustained'at'a'level high enough above 'thebottomofthe'tank, as shown in Figure 3, tofprovi'dehmple fhead room or clearanceforjthe 'w orkm en engaged in "the operation rifeleaningfthetank. I

In theform'of my invention herein illustrated, each of the auxiliarysupportsE is suspended froin'a l'iorizontally disposed cafrrien'Z thatslides in'bearings on the underside offthe roof. 'In'ofrd'er thattheaui'ril-ia'ry supports E may he readily mevea into an'lr out (if theiractive "position, while the 'roof fis-iioating on rthe' liquid inthe'tank, the carriers 2 we slidin'giy mounted in'bearihg' 3 carrid 'by theinner vertical wall oi the pontoon c and bearin 's S that'projectdownwardly from the underside of the 'd'eok l of the roof in spacedrelationship with-the bearings-"3 fan d the pontoon CKis pr'oViHed inits top-'wallwithmanhol'es 4* that are-normally closed by iemovablemanhole "covers 5 theearriers 2 'being so arrangedth'at they can benianipiilate'dfrom theihterior-o'f the pontoon to 'shift the supports Ehorizontally into and'o'ut of "their ac'tivefpo sition. V H

Ealch 6f the horizontally reciprocatingcarriers 2 as provided witha'dependlng rod or i-eg e to which-one or theauxiliarysupports n isattaeheii, land-said auxiliary supports'are prferablyioi'med from'hgillow members that have "some buoyancy, as I have found tl1'at*thistype or construction is desirable, inasmuch the buoyan't auxinarsupports E exert little or no load on the reipr o cating tia rriers 2,and accordingly, do not retard vetti'cal alignment with thepontobnQ'theupper 75 ends of said auxiliary supports will be spacedslightly away from the bottom of the pontoon C,

as shown in Figure 2. Subsequently, when the roof moves downwardly, therods or bars 6 will flex sufiiciently to permit the bottom of thepontoon to contact with the upper end of the auxiliary supports E, andthus cause the weight of the roof .to be transmitted directly to thefixed or stationary supporting means D by the auxiliary supportsE. Inorder to prevent gases from escaping-from the gas spaceof*the-tank'through the bearings 3 in the inner side wall of the pontoonC, said bearings 3 are provided with removable closures 1 which normallyare mounted on or combined'withsaid bearings 3 in such a way as toclosethe openings in the side wall of the ponto'on through which the carriers2 project into the interior of the .pontoon.

'Fromthe foregoing it will be understood that the 'auxiliary supports Eare normally set or adjusted in the position shown in Figure 1. -At suchtimes the fixed or stationary supporting structure D inthetank sustainsthe weight of theroof wheneverthelevel of th'eliquid :0 drops low enoughto causethe pontoon of the roof to rest upon'said supporting structureI). If cleaning of the tank becomes necessary, the manhole covers 5 ofthe pontoon are removed, as shown i'n'Figure2, so a'stolpemnittheclosures 1 of the hearings 3 to be'taken'off, after which thecarriersZ-aifemoveil in a direction to'shift the auxiliary'sup'ports 'Einto operative relationship with the -ponto'on to cause the roof to be[sustained at {a level considerably higher than the level atwhichtherodflies whenthe pontoon of the roof r'ests directly upon thestationary supporting structure D. Whenth'e roof 'isin this position,ample clearance or head room is provided'for'the workmen inside of 'thetank who are engaged in thehfperationof-cleaning "thetank. At thee'oinpl'tionof the cleaningoperation, liquid is again admitted'rtothetarik, and after the liquid level has become high enough to *float' theroof, the auxiliary supports E are slid horizontally backto theirinactive position-and theclosures 1 are-replaced cn the liearirigstinthe side wall of the pontoon.

"Qne "decided aevantagedr a tank roof supporting 3: structure of thekind above eesqnbee, is

that the ope'rator whoadjusts' or mamb iatesn is notapt to make a'hiistake and'set the auxiliary supports in their "finactive position.whenhe intended that sai'disupports should be' set in their 'adtiii13051131011. ThiSdS hCaLliSB "Said auxiliary 1 supports are fastened tohorizontally-slid'abie carriers that are mounted on "the rodf in suchainan'ner that-when the operato'rpulls said carrierstowartlshi'rh,'orfinothe'r words, slides said carriei s outwardly tOwardSthe sidewall (if the I tank, he"-1 nows'that theauxiliary supportswill move intotheir a'ctive position in vertical alignment withthepontoonofthe'roof, "and 'whe'n' he pushes said carriers away fromhimfor pushes them inwardly towards the center of the tank, he knowsthat the auxiliary supports will be shifted out of the zoneof -thepontoon-into their inactive position.

Another desirable feature or characteristic of my improved construction,is that it does not rely on gravity .or .on a separate stop blockattached to the roof, to determine or control the active'pos'ition o'fthe auxiliary support. It is the inner side wall or rim of the potoonthat governs the active position of the auxiliary supports, and saidsupports are fastened to horizontally-slidable carriers, which are ofsuch cross-sectional shape, that they cannot twist or turn, and thuscause the auxiliary supports to assume an improper position. In additionto the above mentioned desirable characteristics, my improvedconstruction is of rugged design, it is easy to install, and theauxiliary supports are hidden from view and well protected from theweather.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:

toon and said pontoon being provided with means that provides access tosaid carriers.

2. The combination of a liquid container, a

floating roof in said container provided at its periphery with adependingv pontoon, stationary supportingmeans for sustaining the roofin comparatively close proximity to the bottom of the container when theroof is' not floating, and horizontally-slidable, auxiliary supports onthe underside of the roof, normally spaced away from the inner edgeportion of the pontoon of the roof but adapted to be moved under theinner edge portion of said pontoon to co-operate with same and with saidstationary supporting means, to

sustain the roof at a higher level than the level at which the roof lieswhen it is sustained by said stationary supporting means, said auxiliarysupports being suspended from horizontallyreciprocating carriers on theunderside of the roof that slide in-bearings in the side wall of saidpontoon.

JOHN H. WIGGINS.

